WO 2007/070267 A1 discloses a diaper having first to fourth conductive paths printed or laminated on an inner surface of an outer cover of the diaper. The first conductive path extends longitudinally from a front region of the diaper to a waist region, through a central region and serves as a reference electrode. A conductive pad is disposed at a front waist band end of the first conductive path. The second to fourth conductive paths take on a serpentine form and are respectively located in the front waist region, the crotch region and a rear waist region of the diaper. Leads connect each of the first to fourth conductive paths to respective conductive pads located at a front waist band portion of the absorbent article.
A signalling device is able to attach to the first to fourth conductive pads at the front waist band portion. The signalling device is configured to apply a potential between the first conductive path and each of the second to fourth conductive paths to be able to separately determine the presence of liquid in the front, crotch and rear diaper regions on the basis of liquid bridging the two conductive paths to form a closed circuit.
A problem with the arrangement of WO 2007/070267 A1 is that the leads extending between the serpentine conductive paths and the conductive pads are in electrical communication with the absorbent core. This means that a short circuit can occur between the leads and the first conductive path or reference electrode, which will give an indication that liquid discharge is present in the serpentine path region when, in fact, the trigger is occurring because of liquid discharge at the lead.
It would be desirable to provide an absorbent article with a wetness detector that reduces or eliminates false detections as described above.
In the arrangement of WO 2007/070267 A1, the wetness detector perform wetness detection in a region separated way, but the layout shown requires liquid discharge to sufficiently laterally spread to be present laterally between the first conductive path or reference electrode and the serpentine conductive paths. In such an architecture, the area in which conductive paths are bridged is skewed off-centre, while the area that will be primarily subject to liquid discharge is a longitudinal centre line of the article.
It is desired to offer at least one wetness detector arrangement that is able to perform detection of a longitudinal extent of a liquid discharge and which is not laterally skewed. Also, it is desired for the absorbent article to be convenient to manufacture.
WO 2007/070267 A1 discloses a more simple structure to the serpentine region based conductive paths described above. In this simpler alternative, the absorbent article has two parallel conductive paths extending longitudinally from a front to a rear of the diaper. While reasonably easy to manufacture, this architecture does not allow determination of longitudinal extent of a liquid discharge. What is desired is an absorbent article that is comparably straightforward to make, but which provides longitudinal wetting discrimination.